Experimental characterization of the thermophysical properties of some selected phase change materials for building applications: Critical input data for numerical simulations

A precise characterization of the thermophysical properties of Phase Change Materials (PCMs) used for the Latent Heat Thermal Energy Storage (LHTES) is necessary for the development and manufacturing of LHTES technologies. The complete input data for Computational Fluid Dynamics (CFD) simulations of PCMs phase transition processes is very lacking in the literature, making it difficult to set up CFD simulations and specially to guarantee the accuracy of the results. The present study focuses on a comprehensive experimental characterization of the thermophysical properties of six PCMs in order to support the numerical studies. Several measurement techniques allowed the characterization of these PCMs. The Anton Paar MCR 102 rheometer was used to determine the viscosity of the six PCMs and their temperature dependency. A TPS 2200 model HotDisk allowed the measurements of the thermal conductivity of both solid and liquid phases of the PCMs, using a temperature-controlled bath. A high-precision in-house experimental setup was developed and validated, for measuring the liquid phase density of PCMs and its temperature dependency. Subsequently, it allowed the determination of the thermal expansion coefficient, which is rare in the literature. Finally, a Differential Scanning Calorimeter (DSC) was used to determine the necessary thermal data for modeling the phase change processes, including latent heat, transition temperatures, and specific heat capacity. Six paraffinic (RT18HC, RT21HC, RT24HC) and bio-based (PT20, PT23, PT25) PCMs, with high potential for buildings application were fully characterized using the aforementioned techniques. The obtained results allowed to establish correlations to consider and integrate the temperature dependence of the thermophysical properties of the analyzed materials in the numerical simulations. This will improve the accuracy of numerical studies using these materials. • Six selected commercial phase change materials were experimentally characterized. • The temperature-dependence of the thermophysical properties was fully established. • An in-house setup was proposed for thermal expansion coefficient determination. • The present results constitute a reliable database for numerical simulations. • The six selected materials have huge potential for buildings heating and cooling.